Inertia and air-operated arming mechanism



June 24, 1958 R ow AL 2,839,998

.INERTIA AND AIR-OPERATED ARMING MECHANISM Filed Jan 15. 1948 a Sheets-Sheet 1 I QrWM't IZODS, L .Jacclh Rahinnvv Laurence. M. Andrews. John W. Euwlimj @QMJ June 24, 1958 J. RABINOW ET AL 2,339,998

INERTIA AND AIR-OPERATED ARMING MECHANISM 3 Sheets-Sheet 2 Filed Jan. 15. 1948 Jam: 1:]: R ab'h-l EJW Laur EI'LCE M. find-r EWS Jul-m W E1 1:: wlin 12 June 24,1958 J, RABINOW'ETAL 2,839,998

INERTIA AND AIR-OPERATED ARMING MECHANISM Filed Jan. 15, 1948 s Sheets-Sheet 3 V 1 I Q 5 -/2 ,0

VIII/II Ems l5 Jail: :1]: R abinmw Laurence M.Flnch-aws JuhnW E EIWHTLH INERTIA AND AIR-OPERATED ARMING MECHANISM e I Jacob Rahinow, Laurence M. Andrews, and John W.

Bowling, Washington, D. C., assignors to the United States of America as represented by the Secretary of the Army Application January 15, 1948, Serial No. 2,533 8 Claims. ((31. 102-s1.2 (Granted under Title 35, U. '5. Code 19 52 sec. 266) The invention described herein may be manufactured tion of normal acceleration resulting from successful dis charge of the projectile. Another object is to provide safety means including an arming wire for the'fuze so arranged that accidental withdrawal of the arming wire can not arm the fuze. Still another object is to provide means requiring both air pressure and inertia forces to accomplish arming of the fuze. object is accomplished by the use of disengaging gears so arranged that arming is initiated andpartly accom plished by means of a propeller, means of a spring. i

The purpose of these elements is to provide a projectile fuze which is fool-proof aspossible inthat it requires a series of conditions to arm the fuze, which conditions and is completed by occur only if the fuzed projectile has beens'afely handled and successfully discharged. This is particularly important in the case of extra-sensitive fuzes such as superquick fuzes or proximity fuzes. I Other objects and advantages of our invention become apparent as the disclosure proceeds.

In the drawings; 7 Fig. 1 is a longitudinal axial partial sectional view of the nose of a projectile embodying our invention, prior to discharge, I

Fig. 2 is a similar view after the projectile has been discharged,

Fig. 3 is a sectional transverse view taken on line 330fFig.l,

Fig. 4 is a sectional transverse view'taken on line 44 of Fig. 2,

Fig. 5 is a longitudinal sectional detail taken on line 55ofFig.3,and I V,

Fig. 6 is a longitudinal sectionaldetail taken on line 66ofFig.4. 3

Fig. 7 is a detail view of the bottom plate showing the gear sector in the final armed position. e i

Referring to Fig. l, the fuze 1 is screwed into the projectile 8 which may be a rocket mounted on an airplane for discharge therefrom against another airplane or a ground target, or it may be any other type of projectile intended to be discharged with high initial acceleration toward a target. Fuze 1 is provided with an airoperated wind vane or turbine 2 which ontraYelling through the air tends to drivea'shaft ZAWhich, in turn, (under the proper operating conditions) drives a gear will More specifically this nited States Patent Ofilice Patented June 24,

.2 train contained within the' section 3 of the fuze which also contains the inertia mechanism of, our invention. When the gear train is elfectively driven by the shaft ata rela tively high speed, it turns arming shaft 16 which carries the detonator rotor 4 with it due to lock pin6,-wl1ich at all times keys rotor 4 to shaft 16. Initially the 'detona'tor' rotor 4 is so orientedthat squib 5 is safely outofline with port 50 and contacts 5A andSB of the squib firing" circuit are similarly out of line. When the arming device is successfully operating, i. e., when normal discharge" occurs, the elements above described will be' effective to' tive to cause a detonation.

rotate the squib 5 from the safety position shown in Fig; 1 to the armed position in which the squib is aligned with elements 5C and 5B so that closing of thesquib circuit by electric fuze means of any suitable typesuch' as a proximity fuze, electric time fuze, etc., will be etfec- The electric fuze elements are not shown in the drawings but the components thereof are "intended to be housed in the empty spaces shown 7 immediately before and behind the mechanism 3- in Fig. 1. Because of the stringent safety requirements of prox imity fuzes, our invention is particularly usefulwith such fuzes and is especiallyadapted for'use with one type of proximity fuze in which the high speed sh'aft'ZA drives an electric generator for energizing the fuze, since this source of power'can then be also used to drive our safety armingmechanism. An arming wire 7 is normally threaded through a suitable bracket 7A on the body-:of the fuze, and through'the vane 2 so as to keep the latter V which time the arming wire is withdrawn.

The main elements of the gear train and inertia mecha-' nism are contained between two flat plates '27 and 28 which are spaced by studs 26. Worm 29 on the end or shaft 2A drives gear 10 which,'in turn, through worm '11' (Fig. 4) drives gear 12. Gear 12 is mounted integrally" with pinion 13 which drives idler: 1 4 loosely mounted'ori 2 respectively. Weight 20 is biased into theforward posi I stud 14A. Idler 14 initially engaged with theteeth of gear sector 15 (Fig. 3). This gear sector 15 is rigidly attached to shaft 16 for rotation therewith;

The initial condition of the mechanism is of coursefthe .safe or unarmed conditionwhich isshown in Figs.v l, 3

and 5. A detent element 24 (Fig. 3) is mounted so as to pivot loosely on the stud 26,'and is provided with a' notch 23. A setback weight 20 is preferbaly formed of two semi circular plates riveted together 'at 20A and is provided with struck-out portions 2013 serving as hinge pins in cooperation with coacting struck-out portions of V plate-27 (Fig; 2) whereby the weight 20 has' a limited amount of angular motion about the axis of its'ihinge pins between two extreme positions shownin Figs. 1 and tion shown in Figs. 1 and 5, by a compression spring 21, the lower end of 'Whichengages plate 28 (Fig. '5) while" the upper end is seated in a depression in weight;2 0. Weight 29 is provided with a finger 22 (see for example" Fig 6 which engages notch 23 of detent 24 in such fashion that when the weight'zll is inits initial position detent 244s in the path of gear sector 15, as shown in Fig. 3, and serves as a stop'for'sector' 15, but when Weight Zil is displaced toits rearward position as by" acceleration forces acting thereon, detentzd ism v d b ii finger 22 to the position shown in Fig. 4, 'allowinglg r a sector 15 to move into the position shown in Fig 4.

If the arming wire 7 were accidentally pulledso as to release the vane 2 while the projectile for' example, a rocket, is mounted below a wing of an'airplane'the vane would start turning, resulting Lin the rotation of gear sector 15, clockwise, as seen in. Fig. .3, and the'gear willf be driven until'it impinges on 'detent'24." Any further turning of the vane would then either'be prevented or else a mechanical failure of the gear train would result due to the large mechanical advantage of the system.

If, however, the projectile were properly fired immediately after the 'arming wire is; pulled; acceleration of the fuze body would cause weight .2010 move 'back compressing spring 21 and moving detent,24 outwardly as shown in Fig; 4. Rotation of the ,vane 2 under this condition would permit the gear sector teeth to move clockwise Without hitting detent 24 until they were completely disengagedfrom the driving idler 14. A spring 18 is mounted around shaft16 andfastened thereto at 18A (Fig. 6) at one end and hooked into plate 28 at the other endat 18B so as to drive the shaft 16 and sector 15 clockwise in the same direction as turned by the action of the vane 2. Spring 18 causes the gear sector 15 to continue its motion after it is. disengaged from the driving idler 14 and drives it forward until the leading edge of the gear sector impinges on detent 25 (Fig. 4) which extends from weight 20 similar to finger 22 (see Figs. 1 and 2). Shaft 2A is now free to-continue rotation but further rotations of the shaft 2A has no effect on the arming system. The arming mechanism has now rotated the arming rotor 74 approximately 90 to the position shown in vFig. 6. This is notsufiicient for arming as another 90f of rotation is necessary for the squib to be properly aligned into firing position. However, it is desirable that the fuze be not fully armed until acceleration has ceased, to insure that it has moved a sufiicient distance from the point, of firing to be safe to the using personnel in the event that. the fuze is so defective that it will detonate immediately on attaining the armed position. This 'is accomplished by the described structure, since detent 25 blocks completion of the arming as long as weight 20 is in the setback position. When the setback force on weight 20 has diminished to the point Where spring 21 can return weight 20 to its initial forward position, then detent 25 moves out of the way of gear sector 15 which is rotated, under the action of spring 18 into final armed position, which is eflt'ected by detent 19 (Figs. 1 and 7) struck up from plate28. Fig. 7 shows the final position of the gear sector relative to plate 28.

r In position the arming shaft has revolved the detonator rotor out of the aligned now readyto function.

i It will beseen that the above described construction accomplishes the objects of the invention, but it will be apparent that other mechanical motions and elements than the ones shown could be used to accomplish the same objects within the scope of the invention as defined by the appended claims. weclaimr e '1 'i 1. Safety arming'mechanism for a projectile fuze, of theftype having an out-of-line powder train interrupter which is-moved into aligned position to arm the fuze, comprising an air driven motor operatively connected with said interrupter to initiate movement thereof toward aligned position, means for releasing the connection of said motor from said interrupter after a predetermined initial motion of said interrupter, and spring means biased to'continue said movement of the interrupter into fully aligned armed position, v

'2. Safety arming mechanism for a projectile fuze of the type having an out-of-line powder train interrupter which is moved into aligned position to arm the fuze, an air driven motor operatively connected with said interrupter for initial movement thereof toward aligned position, means for releasing the connection of: said motor from said interrupter after a predetermined initial motion of said interrupter, spring means biased to continue said movement of the'interrupter into fullyaligned armed position, stop means for preventing said air-driven motor from completing its action, and acceleration-responslve means for disabling said stop means when actuposition and the fuze is.

ated by the acceleration forces of setback resulting from normal discharge of the projectile.

3. Safety arming mechanism for a projectile fuze of the type having an out-of-line powder train interrupter which is rotated into aligned position to arm the fuze, an air driven motor operatively connected with said interrupter for initial movementthereof toward aligned position, means for releasing the connection of said motor from said interrupter after a predetermined initial motion of said interrupter, spring means biased to continue said movement of the interrupter into fully aligned armed position, stop means for preventing said spring from completing its action, andacceleration responsive means for rendering effective said stop means when actuated by the acceleration forces of normal setback, and responsive to cessation of'said setbackto disable said stop means and thereby enable completion of arming of the fuze. g f

4. Safety arming mechanism for a projectile fuze of the type having an out-of-line powder train interrupter which is rotated into aligned position to arm the fuze, an air driven motor operatively connected with said interrupter for initial movement thereof toward aligned position, means for-releasing the connection of said motor from said interrupter after a predetermined initial motion of said interrupter, spring means biased to continue said movement of the interrupter into fully aligned armed position, first stop means for preventing said air-driven motor from completing its action, acceleration-responsive means for disabling said stop means when actuated by the acceleration forces of setback resulting from normal discharge of the projectile, second stop means for preventing said spring means from completing its action, and acceleration responsive means for rendering effective said second 'stopmeans when actuated by the acceleration forces of normal setback, and responsive to cessation of said setback to disable said second stop means and thereby enable completion of arming of the fuze.

- 5.1The invention, as recited in claim 4, wherein said air-driven motor comprises a wind vane, a shaft driven thereby, a reduction gear. train driven by said shaft, a gear sector -driven -by said gear train, a second shaft rotated with said gear sector and a powder train interrupter rotated by said shaft.

. 6. The invention, as recited in claim 5, wherein said gear sector is proportioned to be disengaged from said gear train after partial rotation of said second shaft and said spring means includes a spring tensioned to complete rotation of said second shaft after said disengagement.

'27. The invention, as recited in claim 6, wherein said acceleration responsive means comprises an inertia weight, said first stop means being held thereby into the path of said gear sector and efiective to prevent disengagement of said gear sector and gear train in the normal position and movable by said inertia weight under the force of normal setback out of said path to permitfurther movement of said gear sector under force of said spring.

8. The invention, as recited in claim 7, wherein said second stopmeans comprises a' second stop held by said inertia weight in the path of said gear sector to prevent said gear sector from fully completing its arming rotabut movable by said inertia'weight out of said stopping position upon the cessation of setback.

References Cited in the file of this patent UNITED STATES PATENTS n 'Grauman'n j Oct. 15, 1946 2,420,237; Girouard May 6, 1947 I FOREIGN PATENTS reat Britain- -Iuly 26, 1912 

